1. Field of the Invention
This invention relates to welding helmets and controls therefor, and specifically to welding helmets having automatically controlled eye shields. More particularly, this invention relates to a welder's helmet in which a dark eye shield is moved automatically into position relative to the welder's mask to protect the welder's eyes against injury from the intense flash of a welding arc and which embodies means for ventilating the helmet interior and to clear the eye shield of smoke and fumes.
2. Description of the Prior Art
There have been various attempts in the past to provide an automatic welder's helmet to protect the operator's eyes from the intense welding arc during the welding cycle. As is well known, the intense flash caused by electric arc welding, heli-arc welding, and tack welding and the like, for example, is injurious to the welder's eyes. The typical welder's helmet utilizes a nearly opaque or light radiation absorbing eye piece to block the intense arc light. In some instances, the dark eye piece is permanently affixed to the welder's helmet such that the operator must continuously manually raise and lower his helmet to visually inspect his work. In other cases, the operator can either manually flip up, slide up vertically, rotate out radially, or otherwise move the eye piece to see his work.
One such prior art attempt is U.S. Pat. No. 3,096,430, issued July 2, 1963, which discloses a pneumatically operated eye shield control unit in which the associated electrical circuitry utilizes a time delay relay to assure that the welding arc cannot be struck until the dark eye shield is closed. However, no provision is made for assuring the arc has completely ceased before the dark lens is lowered. Another prior art teaching, typifying prior attempts at automatic welder helmets, is found in U.S. Pat. No. 2,761,046, issued Aug. 28, 1956. This patent discloses a rotary solenoid-controlled mechanism for operating the dark eye shield. The circuitry disclosed in that reference assures that the electrical arc is completed and broken before the shield will re-open. Other prior art devices utilized "Bowden" type wire cable devices to control the dark lens, or a single arm control lever.
A major problem with these and other prior art attempts at automatic welder's helmets has been the presence of cumbersome mechanical linkages and lens mounting frames positioned on the exterior of the face mask of the helmet. These devices required that the helmet, when removed from the operator's head, had to be carefully laid down in only certain positions so as to prevent damage and misadjustment to the lens control. Such exteriorly-mounted components also made for an awkward balance of the helmet when worn.
Another problem with the "Bowden" wire or single control arm type prior art devices is that they tend to bind up in use thereby not allowing the dark lens to close and causing possible eye injury.
Another problem with the previously known automatic welder's helmets is that they often allowed the protective eye shield to be unintentionally opened when the electric arc--which typically completed the circuit controlling the eye shield actuating system--was prematurely broken or otherwise ceased.
Additionally, there has been a continual problem of buildup of unwanted heat and toxic welding fumes within the welder's helmet during long periods of welding, especially when working on pre-heated fabrications. Also there is a need to protect those welders that are sometimes careless and do not properly utilize their helmet, whether of the automatic type or not. There has not been a satisfactory solution to date to overcome these various problems.
The present automatic welder's helmet invention overcomes the foregoing and other problems inherent in the prior art by utilizing the welding torch or electrode holder's control or switch to initiate time-delay relay means which in turn actuates the pneumatic control mechanism closing the helmet's dark eye shield before the arc is energized. A dual lever closing mechanism is used to prevent accidental binding of the dark shield when being closed. Additionally, even if for some reason the welding arc is broken while the operator continues to press the control switch or button, or there is a pressurized air failure, the dark eye lens will automatically close or remain closed thereby assuring protection of the welder's eyes. After the desired welding operation is completed, additional time-delay relay means assures that sufficient time has been expired for the weldment's white afterglow to die off before the pneumatic control mechanism lowers the dark eye shield. This then allows the welder to inspect his work through the clear lens without the need to raise his helmet. Moreover, the compressed air system used to operate the pneumatic eye shield control mechanism is routed through novel means within the welder's helmet to continuously ventilate the helmet during the welding operation. This helmet ventilation feature is used to cool off the welder's head area, to eliminate any foul or toxic welding fumes from the helmet's interior, and, if heated air is used, to prevent moisture from fogging up the helmet's protective lens.
It will be seen that the automatic welder's helmet of the present invention provides increased protection to the welder's eyes; helps to ventilate, cool, and defog the helmet's interior and lenses; and increases welder productivity by eliminating welder down time. The latter occurs because the continuous manual raising and lowering of the welder's helmet or moveable dark lens to visually inspect the work, as required in the prior art devices, is eliminated by the present invention. The present helmet further tends to discourage careless welders from manually holding their helmets up adjacent their faces during short term welding sequences, rather than physically wearing the helmets.
It is therefore an important object of the present invention to provide an automatic welder's helmet having a pneumatic dark eye shield control mechanism to prevent injury to the welder's eyes before, during, and after the welding operation.
It is another object of the present invention to provide an automatic welder's helmet with interior ventilation means for eliminating annoying odors and providing a fresh air supply.
It is yet another object of the present invention to provide a ventilation system for an automatic welder's helmet which may be operated by the raising and lowering of the helmet upon the operator's head, or in response to initiation and termination of the welding cycle.
It is a further object of the present invention to provide electrical and pneumatic control circuitry for an automatic welder's helmet in which there is a time delay between when the dark eye shield is closed and the arc is struck, and a second time delay between when the arc is terminated and the dark eye shield is opened.
It is a still further object to provide control circuitry for an automatic welder's helmet that renders the use of the helmet and an associated welding instrument substantially foolproof.
It is yet a further object to provide a welder's helmet with an automatic dark lens control and ventilating system that is light in weight and can be unobtrusively mounted in the interior of the helmet.
Another object of the invention is to provide an automatic dark shield control system that will automatically close, or remain closed, in the event of a compressed air or electric failure.